Water temperature gauge



FIG. 1 is a left, front perspective view of a water temperature gauge showing my new design;

FIG. 2 is a right side elevational view thereof;

FIG. 3 is a rear elevational view thereof;

FIG. 4 is a front elevational view thereof on a reduced scale.

The broken-line showings of water pipes and shower system are environmental only and form no part of the claimed design. 

The ornamental design for a water temperature gauge, as shown and described. 